EP560\u2005Rare pathology of a malignant uterine myxoid leiomyosarcoma with osteocartilaginous differentiation

Abstract

Introduction/Background Uterine leiomyosarcomas are a rare form of uterine tumours and are often associated with poor survival prognosis. Heterologous differentiation in leiomyosarcomas is an extremely rare phenomenon with less than 15 cases reported in literature to date. We report a case of primary myxoid leiomyosarcoma of the uterus with osteocartilaginous differentiation. Methodology A 44-year old Chinese female first presented to our hospital with complaints of irregular heavy periods and was found to have iron-deficiency anaemia. She underwent a dilatation and curettage which revealed a benign endometrial polyp on a background of late proliferative endometrium. A pelvic ultrasound was performed and she was found to have multiple uterine fibroids with the largest one measuring 4.8 cm. She opted for conservative management but repeated follow up scans showed the fibroid enlarging in size to 8.9 cm over a period of 2 years. In view of enlarging size of fibroid, she was advised for surgery and underwent a total abdominal hysterectomy and bilateral salpingo-oophorectomy. Results Final histology showed a malignant neoplasm with areas of myxoid leiomyosarcoma and smaller areas of osteosarcomatous and cartilaginous differentation, raising the possible differential diagnosis of malignant mesenchymoma arising from the uterus. She was discussed at the gynae-oncology tumour board meeting and conclusion favoured a myxoid leiomyosarcoma. She was offered complete surgical staging but she declined. Her post-operative CT scan of the chest, abdomen and pelvis was clear with no evidence of lymphadenopathy or distant metastasis. She has remained disease-free for 18 months so far. Conclusion Osteocartilaginous differentiation of a malignant uterine myxoid leiomyosarcoma is very rare and very few such cases have been reported in literature. This unique case emphasizes the importance of clinical correlation with radiological and pathological findings in confirming the diagnosis of tumours with unusual histology and presentation. Disclosure Nothing to disclose.